This invention generally relates to a display, more particularly to a display having display lightguide which is shaped into display characters in three dimensions, and to a light collection portion for use in the display. Also, the present invention relates to a light diffusion member provided on the rear surface of a display portion on which a plurality of display characters illuminated by light that is incident thereon from behind. Further, the present invention relates to a display member having display lightguides each provided with a convex portion on which a display character is shaped in three dimensions.
Hitherto, from viewpoint of layout of design, there has been devised a display adapted to irradiate light on display lightguides, which are shaped into display characters in three dimensions, from behind so that the display lightguides luminously display the characters. However, in the case that a point light source, such as an LED, is used as a light source, the farther the location of a part of each of the display characters from the LED, the lower the brightness of the part.
For instance, in the case that as shown in FIG. 18, the shape of a segment constituting a numeral serving as a display character is formed on the display lightguide 11. Moreover, an LED 20 is disposed on the back face of the display lightguide 11 and at the nearly center C in the longitudinal direction Y1 thereof, the luminance in the longitudinal direction Y1 of the segment decreases toward a tip end from the center C. Thus, the related display has problems in that the display character does not have a three-dimensional appearance, and that presentation effects thereof are imparted.
Also, it has been devised to make a surface light source, which is opposed to display characters, by using a liquid crystal display (LCD). This related display has a problem in that the luminance of a liquid crystal display itself is low, thereby the luminance of the display characters is low as a whole
Especially, in the case where a segment is shaped into a display lightguide, it has been devised to make a surface light source, which is shaped according to the shape of the segment, by using a vacuum fluorescent character display tube (VFT). However, a VFT has a gap formed between an illuminant, which serves as a luminous face, and a front glass. Therefore, this related display has problems in that although a VFT 30 is placed just behind the display lightguide 11 shaped into the segment when viewed from just front thereof as illustrated in FIG. 19A, the position of the VFT 30 is shifted from the place located just behind the segment when shifting the line of vision to the left, as illustrated in FIG. 19B.
Also, there has been devised a display adapted to irradiate light on a display portion that is constituted by lightguides, on which display characters are shaped in three dimensions, or by light blocking plates in which the shapes of display characters are cut out, thereby to luminously display the display characters. Moreover, it has been devised to provide a light diffusion plate between the display portion and a light source in the display in such a way as to cause all the display characters to uniformly emit light.
An example of such a display is a seven-segment display shown in FIG. 20A having a display portion, in which seven segments a to g constituting a numeral “8”, and seven light sources 2a to 2g respectively provided on the rear surfaces of the segments a to g. In a case where a light diffusion plate 3 is provided in the seven-segment display in such a manner as to cover all the segments a to g, for example, when a light source 2a provided corresponding to the segment a is caused to emit light, the light is incident on the rear surfaces of the segments b and c through a light diffusion plate 3.
Thus, in a case that light diffusion plates 4 are respectively provided corresponding to the segments a to g independent of one another as shown in FIG. 20B, leakage of light therefrom to the segment other than the segment corresponding to the lighted light source is prevented. However, this related display has a problem in that assembly of the display becomes more troublesome wit increase in the number of components thereof.
Also, from viewpoint of layout of design, there has been devised a display adapted to irradiate light on a display portion having display lightguides each provided with a convex portion, on which a display character are shaped in three dimensions, from behind to thereby luminously display the display characters.
However, in the above related display, the three-dimensional shape of the display character is formed by the lightguide. The related display has problems in that especially, in a case where the display character is shaped on a transparent lightguide in three dimensions, it is difficult to visually cognize the three-dimensional shape, and that the display character cannot be seen as a three-dimensional image, with the result of spoiling the design thereof. Additionally, there have been demands for providing higher quality design in displaying characters in a display for luminously displaying three-dimensional display characters.